Reactor and method for growing carbon nanotube using the same

ABSTRACT

A reactor includes a reactor chamber and a carbon nanotube catalyst composite layer. The reactor chamber has an inlet and an outlet. The carbon nanotube catalyst composite layer is suspended in the reactor chamber, wherein the carbon nanotube catalyst composite layer defines a number of apertures, gases in the reactor chamber penetrate the carbon nanotube catalyst composite layer through the plurality of apertures.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims all benefits accruing under 35 U.S.C. §119 fromChina Patent Application 201210587878.0, filed on Dec. 29, 2012 in theChina Intellectual Property Office, the disclosure of which isincorporated herein by reference.

BACKGROUND

1. Technical Field

The present disclosure relates to reactor and a method for growingcarbon nanotubes using the reactor.

2. Description of the Related Art

Carbon nanotubes (CNT) are very small tube-shaped structures, and haveextremely high electrical conductivity, very small diameter, and atip-surface area near the theoretical limit. Due to these and otherproperties, it has been suggested that CNTs can play an important rolein applications such as microscopic electronics, field emission devices,thermal interface materials, etc. Recently, there are researchesfocusing on how to use the CNT as substrates to grow new particles inthe reactor.

However, because of the limitation of the CNT having a small diameter,it is difficult to utilize the CNT to grow particles as the substrate inthe reactor.

What is needed, therefore, is providing a reactor that can overcome theabove-described shortcomings.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the embodiments can be better understood with referenceto the following drawings. The components in the drawings are notnecessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the embodiments. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 is schematic view of one embodiment of a reactor.

FIG. 2 shows a schematic view of a carbon nanotube catalyst compositelayer in the reactor of FIG. 1.

FIG. 3 shows a scanning electron microscope (SEM) image of oneembodiment of a drawn carbon nanotube film.

FIG. 4 shows a schematic view of one embodiment of a carbon nanotubesegment of a drawn carbon nanotube film of FIG. 3.

FIG. 5 shows a SEM image of one embodiment of a plurality of carbonnanotube films stacked in a cross order.

FIG. 6 shows a SEM image of one embodiment of an untwisted carbonnanotube wire.

FIG. 7 shows a SEM image of one embodiment of a twisted carbon nanotubewire.

FIG. 8 is a schematic view of one embodiment of growing carbon nanotubesusing the reactor of FIG. 1.

FIG. 9 shows a photo of the carbon nanotube catalyst composite layerbeing heated.

FIG. 10 shows a schematic view of another embodiment of a reactor.

FIG. 11 is a schematic view of one embodiment of growing carbon nanotubeusing the reactor of FIG. 10.

FIG. 12 shows a schematic view of another embodiment of a reactor.

DETAILED DESCRIPTION

The disclosure is illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings in which likereferences indicate similar elements. It should be noted that referencesto “an” or “one” embodiment in this disclosure are not necessarily tothe same embodiment, and such references mean at least one.

Referring to FIG. 1, a reactor 10 of one embodiment includes a reactorchamber 13, a carbon nanotube catalyst composite layer 14, and a support16. The carbon nanotube catalyst composite layer 14 is suspended andfixed in the reactor chamber 13 through the support 16.

The reactor chamber 13 receives the carbon nanotube catalyst compositelayer 14 therein. The reactor chamber 13 has an inlet 11 and an outlet12. The inlet 11 is configured for introducing a carbon-containing gasinto the reactor chamber 13, thus producing (i.e., acting as a sourceof) carbon atoms for growing the carbon nanotube film (not shown). Theoutlet 12 is configured for allowing an exhaust gas to beevacuated/discharged therefrom. In one embodiment, the inlet 11 and theoutlet 12 are located at opposite sidewalls of the reactor chamber 13,and the carbon-containing gas can flow from the inlet 11 towards theoutlet 12 along a direct path, and thus the exhaust gas can bedischarged timely.

The reactor chamber 13 may have a circular, elliptic, triangular,rectangular, other regular polygonal or irregular polygonal profile inview of a cross section of the reactor chamber 13. The reactor chamber13 may be made of a material with a high temperature resistance andchemically stable performance. For example, the reactor chamber 13 maybe made of quartz, ceramic, stainless steel or the like. In the presentembodiment, the reactor chamber 13 is a tube, and has a circular crosssection. An inner radius of the reactor chamber 13 can range from about1 centimeter to about 20 centimeters. In one embodiment, the innerradius of the reactor chamber 13 ranges from about 2.5 centimeters toabout 10 centimeters. Thus the carbon nanotube catalyst composite layer14 can be easily received into the reactor chamber 13, and firmly fixedin the reactor chamber 13. A length of the reactor chamber 13 can rangefrom about 2 centimeters to about 50 centimeters. In one embodiment, thelength of the reactor chamber 13 is about 20 centimeters, and the innerradius of the reactor chamber 13 is about 2.5 centimeters.

The carbon nanotube catalyst composite layer 14 is received in thereactor chamber 13, and spaced from the inlet 11 and the outlet 12. Anangle α is existed between a surface of the carbon nanotube catalystcomposite layer 14 and a flow direction of gases in the reactor chamber13. The angle α is greater than 0 degrees, smaller than or equal to 90degrees. In one embodiment, the angle α is equal to 90 degrees, thus theflow direction of the gases flows perpendicular to the surface of thecarbon nanotube catalyst composite layer 14. The shape of the carbonnanotube catalyst composite layer 14 can be selected according to thecross section of the reactor chamber 13, such as circular, elliptic,triangular or rectangular. The surface of the carbon nanotube catalystcomposite layer 14 can be planar, curved, or wrinkled. An area of thecarbon nanotube catalyst composite layer 14 can range from about 0.5square centimeters to about 100 square centimeters. In one embodiment,the carbon nanotube catalyst composite layer 14 is a shape ofrectangular. The surface of the carbon nanotube catalyst compositedlayer 14 is planar, and face to the inlet 11.

The carbon nanotube catalyst composite layer 14 defines a plurality ofapertures 142 allowing gases flow through. The plurality of apertures142 forms a plurality of channels between the inlet 11 and the outlet12. The gases in the reactor chamber 13 can flow through the pluralityof apertures 142. The carbon nanotube catalyst composite layer 14 issuspended in the reactor chamber 13. The carbon nanotube catalystcomposite layer 14 can suspend in the reactor chamber 13 via the support16. The support 16 can be in a shape of a ring fixed on the inner wallof the reactor chamber 13, and the carbon nanotube catalyst compositelayer 14 is fixed on the support 16. A portion of the carbon nanotubecatalyst composite layer 14 inside the ring is suspended. The support 16can also in a shape of grid, and edge of the grid is fixed in thereactor chamber 13. The carbon nanotube catalyst composite layer 14 isattached on the grid. A material of the support 16 can be metal such asgold, silver, or aluminum. The material of the support 16 can also beinsulated material such as ceramic. The carbon nanotube composite layer14 can also be directly fixed on the inner wall of the reactor chamber13. Edge of the carbon nanotube catalyst composited layer 14 can befixed on the inner wall via welding, attaching method, and other portionof the carbon nanotube catalyst composite layer 14 is suspended. Thusthe support 16 can be omitted.

While the surface of the carbon nanotube catalyst composite layer 14 isplanar, the gases in the reactor chamber 13 flows substantiallyperpendicular to the surface of the carbon nanotube catalyst compositelayer 14. While the surface of the carbon nanotube catalyst compositelayer 14 is curved or wrinkled, the gases in the reactor chamber 13flows penetrate through the plurality of apertures 142 of the carbonnanotube catalyst composite layer 14. Furthermore, larger carbonnanotube catalyst composite layer 14 can be located into the reactorchamber 13.

The carbon nanotube catalyst composite layer 14 includes a carbonnanotube layer 147 and a plurality of catalyst particles 148 uniformlydispersed on the carbon nanotube layer 147. The carbon nanotube layer147 is a continuous and integrated structure. The carbon nanotube layer147 includes a plurality of carbon nanotubes oriented substantiallyparallel with the surface of the carbon nanotube layer 147. The carbonnanotubes in the carbon nanotube layer 147 can be single-walled,double-walled, or multi-walled carbon nanotubes. The length and diameterof the carbon nanotubes can be selected according to need. The thicknessof the carbon nanotube layer 147 can be in a range from about 1 nm toabout 100 μm, for example, about 10 nm, 100 nm, 200 nm, 1 μm, 10 μm or50 μm.

Referring to FIG. 2, the carbon nanotube layer 147 forms a patternedstructure. The patterned carbon nanotube layer 147 defines the pluralityof apertures 142. The plurality of apertures 142 can be uniformlydispersed in the carbon nanotube layer 147. The plurality of apertures142 extend throughout the carbon nanotube layer 147 along the thicknessdirection thereof. The aperture 142 can be a hole defined by severaladjacent carbon nanotubes, or a gap defined by two substantiallyparallel carbon nanotubes and extending along axial direction of thecarbon nanotubes. The size of the aperture 142 can be the diameter ofthe hole or width of the gap, and the average aperture size can be in arange from about 10 nm to about 500 μm, for example, about 50 nm, 100nm, 500 nm, 1 μm, 10 μm, 80 μm or 120 μm. The hole-shaped apertures 142and the gap-shaped apertures 142 can exist in the patterned carbonnanotube layer 147 at the same time. The sizes of the apertures 142within the same carbon nanotube layer 147 can be different. In oneembodiment, the sizes of the apertures 142 are in a range from about 10nm to about 10 μm. A duty factor of the carbon nanotube layer 147 can bein a range from about 1:100 to about 100:1, for example, about 1:10,1:2, 1:4, 4:1, 2:1 or 10:1. In one embodiment, the duty factor of thecarbon nanotube layer 147 is in a range from about 1:4 to about 4:1.

The carbon nanotubes of the carbon nanotube layer 147 can be orderlyarranged to form an ordered carbon nanotube structure or disorderlyarranged to form a disordered carbon nanotube structure. The term‘disordered carbon nanotube structure’ includes, but is not limited to,a structure where the carbon nanotubes are arranged along many differentdirections, and the aligning directions of the carbon nanotubes arerandom. The number of the carbon nanotubes arranged along each differentdirection can be substantially the same (e.g. uniformly disordered). Thedisordered carbon nanotube structure can be isotropic. The carbonnanotubes in the disordered carbon nanotube structure can be entangledwith each other. The term ‘ordered carbon nanotube structure’ includes,but is not limited to, a structure where the carbon nanotubes arearranged in a consistently systematic manner, e.g., the carbon nanotubesare arranged approximately along a same direction and/or have two ormore sections within each of which the carbon nanotubes are arrangedapproximately along a same direction (different sections can havedifferent directions).

In one embodiment, the carbon nanotubes in the carbon nanotube layer 147are arranged to extend along the direction substantially parallel to thecarbon nanotube catalyst composite layer 14 to obtain greater gasestransmission. After being placed in the reactor chamber 13, the carbonnanotubes in the carbon nanotube layer 147 are arranged to extend alongthe direction substantially perpendicular to the flow direction of thegases. In one embodiment, all the carbon nanotubes in the carbonnanotube layer 147 are arranged to extend along the same direction. Inanother embodiment, some of the carbon nanotubes in the carbon nanotubelayer 147 are arranged to extend along a first direction, and some ofthe carbon nanotubes in the carbon nanotube layer 147 are arranged toextend along a second direction, perpendicular to the first direction.

The carbon nanotube layer 147 is a free-standing structure. The term“free-standing structure” means that the carbon nanotube layer 147 cansustain the weight of itself when it is hoisted by a portion thereofwithout any significant damage to its structural integrity. Thus, thecarbon nanotube layer 147 can be suspended by the support 16. Thefree-standing carbon nanotube layer 147 can be laid on the support 16directly and easily. Thus the carbon nanotube catalyst composite layer14 is also a free-standing structure. The plurality of catalystparticles 148 is uniformly dispersed in the free-standing carbonnanotube layer 147.

The carbon nanotube layer 147 can be a substantially pure structure ofthe carbon nanotubes, with few impurities and chemical functionalgroups. The carbon nanotube layer 147 can be a composite including acarbon nanotube matrix and non-carbon nanotube materials. The non-carbonnanotube materials can be graphite, graphene, silicon carbide, boronnitride, silicon nitride, silicon dioxide, diamond, amorphous carbon,metal carbides, metal oxides, or metal nitrides. The non-carbon nanotubematerials can be coated on the carbon nanotubes of the carbon nanotubelayer 147 or filled in the apertures 142. In one embodiment, thenon-carbon nanotube materials are coated on the carbon nanotubes of thecarbon nanotube layer 147 so the carbon nanotubes can have a greaterdiameter and the apertures 142 can have a smaller size. The non-carbonnanotube materials can be deposited on the carbon nanotubes of thecarbon nanotube layer 147 by CVD or physical vapor deposition (PVD),such as sputtering.

Furthermore, the carbon nanotube layer 147 can be treated with anorganic solvent after being placed on the epitaxial growth surface 101so the carbon nanotube layer 147 can be firmly attached on the epitaxialgrowth surface 101. Specifically, the organic solvent can be applied tothe entire surface of the carbon nanotube layer 147 or the entire carbonnanotube layer 147 can be immersed in an organic solvent. The organicsolvent can be volatile, such as ethanol, methanol, acetone,dichloroethane, chloroform, or mixtures thereof. In one embodiment, theorganic solvent is ethanol.

The carbon nanotube layer 147 can include at least one carbon nanotubefilm, at least one carbon nanotube wire, or a combination thereof. Inone embodiment, the carbon nanotube layer 147 can include a singlecarbon nanotube film or two or more stacked carbon nanotube films. Thus,the thickness of the carbon nanotube layer 147 can be controlled by thenumber of the stacked carbon nanotube films. The number of the stackedcarbon nanotube films can be in a range from about 2 to about 100, forexample, about 10, 30, or 50. In one embodiment, the carbon nanotubelayer 147 can include a layer of parallel and spaced carbon nanotubewires. The carbon nanotube layer 147 can also include a plurality ofcarbon nanotube wires crossed or weaved together to form a carbonnanotube net. The distance between two adjacent parallel and spacedcarbon nanotube wires can be in a range from about 0.1 μm to about 200μm. In one embodiment, the distance between two adjacent parallel andspaced carbon nanotube wires can be in a range from about 10 μm to about100 μm. The size of the apertures 142 can be controlled by controllingthe distance between two adjacent parallel and spaced carbon nanotubewires. The length of the gap between two adjacent parallel carbonnanotube wires can be equal to the length of the carbon nanotube wire.It is understood that any carbon nanotube structure described can beused with all embodiments.

In one embodiment, the carbon nanotube layer 147 includes at least onedrawn carbon nanotube film. A drawn carbon nanotube film can be drawnfrom a carbon nanotube array that is able to have a film drawntherefrom. The drawn carbon nanotube film includes a plurality ofsuccessive and oriented carbon nanotubes joined end-to-end by van derWaals attractive force therebetween. The drawn carbon nanotube film is afree-standing film. Referring to FIGS. 3 and 4, each drawn carbonnanotube film includes a plurality of successively oriented carbonnanotube segments 143 joined end-to-end by van der Waals attractiveforce therebetween. Each carbon nanotube segment 143 includes aplurality of carbon nanotubes 145 parallel to each other, and combinedby van der Waals attractive force therebetween. Some variations canoccur in the drawn carbon nanotube film. The carbon nanotubes 145 in thedrawn carbon nanotube film are oriented along a preferred orientation.The drawn carbon nanotube film can be treated with an organic solvent toincrease the mechanical strength and toughness, and reduce thecoefficient of friction of the drawn carbon nanotube film. A thicknessof the drawn carbon nanotube film can range from about 0.5 nm to about100 μm. The drawn carbon nanotube film can be fixed in the reactorchamber 13 directly.

Referring to FIG. 5, the carbon nanotube layer 147 can include at leasttwo stacked drawn carbon nanotube films. In other embodiments, thecarbon nanotube layer 147 can include two or more coplanar carbonnanotube films, and each coplanar carbon nanotube film can includemultiple layers. Additionally, if the carbon nanotubes in the carbonnanotube film are aligned along one preferred orientation (e.g., thedrawn carbon nanotube film), an angle can exist between the orientationsof carbon nanotubes in adjacent films, whether stacked or adjacent.Adjacent carbon nanotube films are combined by the van der Waalsattractive force therebetween. An angle between the aligned directionsof the carbon nanotubes in two adjacent carbon nanotube films can rangefrom about 0 degrees to about 90 degrees. If the angle between thealigned directions of the carbon nanotubes in adjacent stacked drawncarbon nanotube films is larger than 0 degrees, a plurality ofmicropores is defined by the carbon nanotube layer 147. Referring toFIG. 5, the carbon nanotube layer 147 shown with the angle between thealigned directions of the carbon nanotubes in adjacent stacked drawncarbon nanotube films is 90 degrees. Stacking the carbon nanotube filmswill also add to the structural integrity of the carbon nanotube layer147, and the aggregation of the catalyst particles 148 can be avoided.Thus the catalyst particles 148 can be uniformly dispersed in the carbonnanotube layer 147, and can be fully reacted with the gases.

In another embodiment, the carbon nanotube layer 147 can include apressed carbon nanotube film. The pressed carbon nanotube film can be afree-standing carbon nanotube film. The carbon nanotubes in the pressedcarbon nanotube film are arranged along a same direction or arrangedalong different directions. The carbon nanotubes in the pressed carbonnanotube film can rest upon each other. Adjacent carbon nanotubes areattracted to each other and combined by van der Waals attractive force.An angle between a primary alignment direction of the carbon nanotubesand a surface of the pressed carbon nanotube film is about 0 degrees toapproximately 15 degrees. The greater the pressure is applied, thesmaller the angle formed. If the carbon nanotubes in the pressed carbonnanotube film are arranged along different directions, the carbonnanotube layer 147 can be isotropic.

In another embodiment, the carbon nanotube layer 147 includes aflocculated carbon nanotube film. The flocculated carbon nanotube filmcan include a plurality of long, curved, disordered carbon nanotubesentangled with each other. Furthermore, the flocculated carbon nanotubefilm can be isotropic. The carbon nanotubes can be substantiallyuniformly dispersed in the carbon nanotube film. Adjacent carbonnanotubes are acted upon by van der Waals attractive force to form anentangled structure with micropores defined therein. It is understoodthat the flocculated carbon nanotube film is very porous. Sizes of themicropores can be less than 10 μm. The porous nature of the flocculatedcarbon nanotube film will increase the specific surface area of thecarbon nanotube layer 147. Additionally, because the carbon nanotubes inthe carbon nanotube layer 147 are entangled with each other, the carbonnanotube layer 147 employing the flocculated carbon nanotube film hasexcellent durability, and can be fashioned into desired shapes with alow risk to the integrity of the carbon nanotube layer 147. In someembodiments, the flocculated carbon nanotube film is a free-standingstructure because the carbon nanotubes being entangled and adheredtogether by van der Waals attractive force therebetween.

The carbon nanotube wire can be untwisted or twisted. Treating the drawncarbon nanotube film with a volatile organic solvent can form theuntwisted carbon nanotube wire. Specifically, the organic solvent isapplied to soak the entire surface of the drawn carbon nanotube film.During the soaking, adjacent parallel carbon nanotubes in the drawncarbon nanotube film will bundle together, due to the surface tension ofthe organic solvent as it volatilizes. Thus, the drawn carbon nanotubefilm will be shrunk into untwisted carbon nanotube wire. Referring toFIG. 6, the untwisted carbon nanotube wire includes a plurality ofcarbon nanotubes substantially oriented along a same direction (i.e., adirection along the length of the untwisted carbon nanotube wire). Thecarbon nanotubes are parallel to the axis of the untwisted carbonnanotube wire. Specifically, the untwisted carbon nanotube wire includesa plurality of successive carbon nanotube segments joined end to end byvan der Waals attractive force therebetween. Each carbon nanotubesegment includes a plurality of carbon nanotubes substantially parallelto each other, and combined by van der Waals attractive forcetherebetween. The carbon nanotube segments can vary in width, thickness,uniformity, and shape. Length of the untwisted carbon nanotube wire canbe arbitrarily set as desired. A diameter of the untwisted carbonnanotube wire ranges from about 0.5 nm to about 100 μm.

The twisted carbon nanotube wire can be formed by twisting a drawncarbon nanotube film using a mechanical force to turn the two ends ofthe drawn carbon nanotube film in opposite directions. Referring to FIG.7, the twisted carbon nanotube wire includes a plurality of carbonnanotubes helically oriented around an axial direction of the twistedcarbon nanotube wire. Specifically, the twisted carbon nanotube wireincludes a plurality of successive carbon nanotube segments joined endto end by van der Waals attractive force therebetween. Each carbonnanotube segment includes a plurality of carbon nanotubes parallel toeach other, and combined by van der Waals attractive force therebetween.Length of the carbon nanotube wire can be set as desired. A diameter ofthe twisted carbon nanotube wire can be from about 0.5 nm to about 100μm. Further, the twisted carbon nanotube wire can be treated with avolatile organic solvent after being twisted. After being soaked by theorganic solvent, the adjacent paralleled carbon nanotubes in the twistedcarbon nanotube wire will bundle together, due to the surface tension ofthe organic solvent when the organic solvent volatilizes. The specificsurface area of the twisted carbon nanotube wire will decrease, whilethe density and strength of the twisted carbon nanotube wire will beincreased.

Referring to FIG. 8, the plurality of catalyst particles 148 can bedeposited on the carbon nanotube layer 147 via electron beamevaporation, thermal chemical vapor deposition, or sputtering method.The catalyst particles 148 can form as a catalyst layer in a thicknessranges from about 2 nm to about 500 nm. A material of the catalystparticle 15 can be Fe, Co, Ni, or any alloy of them. A diameter of thecatalyst particle 15 ranges from about 5 nm to about 10 nm. Theplurality of catalyst particles 148 is uniformly dispersed in the carbonnanotube layer 147. The plurality of catalyst particles 148 can beuniformly attached and dispersed on the surface of the plurality ofcarbon nanotubes via van der Waals force. The plurality of catalystparticles 148 can also be fixed in the plurality of apertures 142, thusthe aggregation of the plurality of catalyst particle 15 can be avoided.While the diameter of the catalyst particle 15 is greater than the sizeof the aperture 142, the catalyst particle 15 can be partly fixed in theaperture 142. While the diameter of the catalyst particle 15 issubstantially equal to the size of the aperture 142, the catalystparticle 15 can be embedded the aperture 142. In one embodiment, amaterial of the catalyst particle is about 8 nanometers, and thethickness of the catalyst layer is about 5 nanometers.

A method of growing carbon nanotube with the reactor 10 includesfollowing steps:

(S11) providing the reactor 10;

(S12) introducing a mixture of a carbon source gas and a carrier gasinto the reactor chamber 13; and

(S13) heating the carbon nanotube catalyst composite layer 14 in thereactor 10 to grow carbon nanotubes.

In step (S12), the mixture is introduced into the reactor chamber 13through the inlet 11. An angle between the flow direction of the mixtureand the surface of the carbon nanotube catalyst composite layer 14 isgreater than 0 degrees and smaller or equal to 90 degrees. In oneembodiment, the flow direction of the mixture is substantiallyperpendicularly with the surface of the carbon nanotube catalystcomposite layer 14, and the mixture flow through the plurality of theapertures 142. Furthermore, the mixture flow out of the reactor chamber13 through the outlet 12. A flow speed of the mixture introducing intothe reactor chamber 13 is substantially equal to a flow speed of themixture flow out of the chamber 13. Therefore, the carbon source gas inthe reactor chamber can be updated to maintain density of the carbonsource gas.

The flow direction of the mixture is substantially perpendicular to thecarbon nanotube catalyst composite layer 14, and the mixture flowspenetrate the plurality of apertures 142. Thus the carbon source gas canbe fully reacted with the catalyst particles 148, and the quality of thecarbon nanotubes grown in the reactor 10 will be improved. Furthermore,the plurality of catalyst particles 148 is firmly fixed in the carbonnanotube layer 147, thus the flow of the gases cannot affect thedistribution of the plurality of catalyst particles 148. Thus theaggregation of the plurality of catalyst particles 148 can beeffectively avoided. The growing speed of the carbon nanotubes dependson the ratio between the temperature of the plurality of catalystparticles 148 and the temperature of the reactor 10. Therefore, thegrowing speed of the carbon nanotubes can be controlled via controllingthe flow speed and pressure of the mixture, ensuring that the flow speedand pressure of the mixture cannot break the carbon nanotube catalystcomposite layer 15.

The carrier gas can be a noble gas, nitrogen, or hydrogen. The carriergas can also be used to adjust the pressure of the furnace 19. Thecarbon source gas can be a hydrocarbon such as methane, acetylene,ethylene or ethane. The ratio of the carbon source gas and theprotective gas can be about 1:1 to about 5:1. In one embodiment, thecarrier gas is argon and can be introduced at a flow rate of 100 sccm.The carbon source gas is ethylene and can be introduced at a flow rateof 1000 sccm.

In step (S13), the reactor chamber 13 can be heated to a reactiontemperature to grow carbon nanotubes via a heating device (not shown).In one embodiment, the reactor chamber 13 can be heated by introducingan electric current into the carbon nanotube layer 147 via a firstelectrode 144 and a second electrode 146. The first electrode 144 andthe second electrode 146 are spaced from each other and electricallyconnected to the carbon nanotube layer 147.

Referring to FIG. 8 and FIG. 9, a voltage is applied between the firstelectrode 144 and the second electrode 146 via a power supply 140, andthe electric current is introducing into the carbon nanotube layer 147.The carbon nanotube layer 147 can transfer electric energy to heateffectively. The voltage can be selected according to the length of thecarbon nanotube layer 147 and the diameter of the carbon nanotubes. Inone embodiment, the diameter of the carbon nanotubes is about 5nanometers, and the voltage is about 40 V. During the process of heatingthe carbon nanotube layer 147, the temperature of the carbon nanotubelayer 147 rapidly increases due to Joule-heating. The carbon nanotubelayer 147 is heated to a temperature in a range from about 500° C. toabout 900° C. Furthermore, the temperature of the reactor chamber 13only ranges from about 30° C. to about 50° C. Thus a greater temperaturedifference is existed between the carbon nanotube layer 147 and thereactor chamber 13. Therefore, the growing speed of the carbon nanotubeson the carbon nanotube layer 147 can be improved. The reacting timeranges from about 30 minutes to about 60 minutes.

Furthermore, during the process of applying a voltage to the carbonnanotube layer 147, a heating device (not shown) can be used to heat thereactor chamber 13 to increase the growing speed of the carbonnanotubes.

The reactor 10 has following advantages. First, due to the chemicalstability of the carbon nanotube layer 147, the carbon nanotubes in thecarbon nanotube layer 147 cannot react with the catalyst particles 148.Second, the carbon nanotubes in the carbon nanotube layer 147 have greatsurface area, thus the carbon nanotubes have great attractive force, andthe catalyst particles 148 can be directly and firmly fixed on thesurface of carbon nanotubes, the additive can be avoided. Third, thecarbon nanotube layer 147 defines the plurality of apertures 142, thusthe catalyst particles 148 can be effectively embedded into theplurality of apertures 142, and aggregation and deactivation of thecatalyst particles 148 during growing process can be avoided. Fourth,the carbon nanotube layer 147 can transfer electric energy to heateffectively, and the reactor chamber 13 can be heated by directlyintruding an electric current into the carbon nanotube layer 147. Thus,the heating device is not needed, and the reactor is low in cost.

Referring to FIG. 10, a reactor 20 of one embodiment includes a reactorchamber 13, and a plurality of carbon nanotube catalyst composite layers14 spaced from each other in the reactor chamber 13. The reactor chamber13 includes an inlet 11 and an outlet 12 on the two opposite ends of thereactor chamber 13. The plurality of carbon nanotube catalyst compositelayer 14 is suspended in the chamber 13 and arranged along an axis fromthe inlet 11 to the outlet 12. The structure of reactor 20 is similar tothe structure of reactor 10, except that the reactor 20 includes aplurality of carbon nanotube catalyst composite layers 14.

The distance between adjacent two carbon nanotube catalyst compositelayers 14 can be same or different. In one embodiment, the plurality ofcarbon nanotube catalyst composite layers is spaced with a certaindistance. The distance can range from about 2 centimeters to about 50centimeters.

Referring to FIG. 11, a method of growing carbon nanotubes with reactor20 includes following steps:

(S21) providing a reactor 20;

(S22) introducing a mixture of a carbon source gas and a carrier gasinto the reactor chamber 13, and the mixture successively penetratingthe plurality of carbon nanotube catalyst composite layer 14; and

(S23) heating the plurality of carbon nanotube catalyst composite layers14 in the reactor 20 to grow carbon nanotubes.

In step (S22), the mixture is introduced into the reactor chamber 13through the inlet 11, and flows through the plurality of carbon nanotubecatalyst composite layers 14. Thus the carbon source gas cansuccessively react with the plurality of carbon nanotube catalystcomposite layers 14. Therefore the carbon source gas can be effectivelydecomposed, and the productivity can be improved.

In step (S23), the plurality of carbon nanotube catalyst compositelayers 14 can be heated at the same time, or selectively heated. In oneembodiment, the plurality of carbon nanotube catalyst composite layers14 is electrically connected to a first electrode 144 and a secondelectrode 146. The plurality of carbon nanotube catalyst compositelayers 14 is electrically connected in parallel between the firstelectrode 144 and the second electrode 146. While applying a voltagebetween the first electrode 144 and the second electrode 146, theelectric current can be introduced into the plurality of carbon nanotubecatalyst composite layers 14 to heat them. Furthermore, a switch (notshown) can be applied between each of the plurality of carbon nanotubecatalyst composite layers 14 and the first electrode 144 or the secondelectrode 146. Thus each of the plurality of carbon nanotube catalystcomposite layers 14 can be independently controlled.

The reactor 20 has following advantages. First, the carbon nanotubes canbe grown on the plurality of carbon nanotube catalyst composite layers14 at the same time, thus the productivity can be improved. Second,carbon source gas can successively flow though the plurality of carbonnanotube catalyst composite layer 14, thus the carbon source gas can beeffectively reacted with the carbon nanotube catalyst particles. Third,the plurality of carbon nanotube catalyst composite layer 14 can beindependently controlled, and the electric can be selectively introducedinto the plurality of carbon nanotube catalyst composite layer 14. Evenif one of the plurality of carbon nanotube catalyst composite layers 14cannot work normally, other carbon nanotube catalyst composite layers 14can still work, thus the lifespan of the reactor 20 can be prolonged.

Referring to FIG. 12, a reactor 30 of one embodiment includes a reactorchamber 13 and a plurality of carbon nanotube catalyst composite layers14 spaced from each other in the reactor chamber 13. The reactor 30includes an inlet 11 and an outlet 12 spaced from the inlet 11. Gasesflow from the inlet 11 to the outlet 22. The plurality of carbonnanotube catalyst composite layer 14 is aligned along a flow directionof the gases. The structure of reactor 30 is similar to the structure ofreactor 20, except that the reactor chamber 13 of reactor 30 is abending structure. In one embodiment, a cross section of the reactor 30is circular, and the reactor 30 includes a plurality of bending. Thebended reactor chamber 13 can effectively utilize the limited space togrow a number of carbon nanotubes.

Depending on the embodiment, certain of the steps of methods describedmay be removed, others may be added, and that order of steps may bealtered. It is also to be understood that the description and the claimsdrawn to a method may include some indication in reference to certainsteps. However, the indication used is only to be viewed foridentification purposes and not as a suggestion as to an order for thesteps.

It is to be understood that the above-described embodiments are intendedto illustrate rather than limit the disclosure. Variations may be madeto the embodiments without departing from the spirit of the disclosureas claimed. It is understood that any element of any one embodiment isconsidered to be disclosed to be incorporated with any other embodiment.The above-described embodiments illustrate the scope of the disclosurebut do not restrict the scope of the disclosure.

What is claimed is:
 1. A reactor comprising: a reactor chambercomprising an inlet and an outlet; a carbon nanotube catalyst compositelayer suspended in the reactor chamber, wherein the carbon nanotubecatalyst composite layer is a continuous and free-standing structure,and the carbon nanotube catalyst composite layer comprises a carbonnanotube layer and a plurality of catalyst particles dispersed in thecarbon nanotube layer; the carbon nanotube catalyst composite layerdefines a plurality of apertures, the plurality of apertures areconfigured to facilitate gases to flow from the inlet to the outlet ofthe reactor chamber.
 2. The reactor of claim 1 wherein a surface of thecarbon nanotube catalyst composite layer facing the inlet is planar. 3.The reactor of claim 1 wherein the carbon nanotube layer provides thefree-standing structure of the carbon nanotube catalyst composite layer,and the plurality of catalyst particles are directly attached on asurface of the carbon nanotube layer.
 4. The reactor of claim 1 whereinthe plurality of apertures extend through a thickness of the carbonnanotube catalyst composite layer.
 5. The reactor of claim 4, wherein asize of the plurality of apertures ranges from about 5 nanometers toabout 10 nanometers.
 6. The reactor of claim 5, wherein the plurality ofcatalyst particles are embedded into the plurality of apertures.
 7. Thereactor of claim 1, wherein the at least one carbon nanotube filmcomprises a plurality of carbon nanotubes oriented substantially alongan alignment direction, the alignment direction being substantiallyparallel to the carbon nanotube catalyst composite layer.
 8. The reactorof claim 7, wherein the carbon nanotube catalyst composite layercomprises at least two carbon nanotube films stacked on each other, anangle between the alignment directions of adjacent of the at least twocarbon nanotube films ranges from about 0 degrees to about 90 degrees.9. The reactor of claim 1, wherein a surface of the carbon nanotubecatalyst composite layer is configured to be perpendicular to a gas flowdirection and to facilitate the gas penetrating through the plurality ofapertures.
 10. The reactor of claim 1, further comprising a plurality ofcarbon nanotube catalyst composite layers aligned along a flow directionof the gases.
 11. The reactor of claim 10, wherein the plurality ofcarbon nanotube catalyst composite layers are spaced from each other.12. The reactor of claim 1, wherein the reactor chamber is configuredwith a plurality of bends between the inlet and the outlet.
 13. Areactor comprising: a reactor chamber comprising an inlet and an outlet;a carbon nanotube catalyst composite layer suspended in the reactorchamber, wherein the carbon nanotube catalyst composite layer comprisesa carbon nanotube layer and a plurality of catalyst particles dispersedin the carbon nanotube layer, and the carbon nanotube layer is afree-standing structure; and the carbon nanotube layer defines aplurality of apertures, the plurality of apertures extend through athickness of the carbon nanotube catalyst composite layer to facilitategases to flow from the inlet to the outlet of the reactor chamber. 14.The reactor of claim 13, wherein the carbon nanotube layer comprises aplurality of carbon nanotubes aligned parallel to a surface of thecarbon nanotube catalyst composite layer.
 15. The reactor of claim 13,further comprising a first electrode and a second electrode spaced fromeach other and electrically connected to the carbon nanotube layer. 16.The reactor of claim 15, wherein the first electrode and the secondelectrode are configured to supply a current into the carbon nanotubelayer to heat the plurality of catalyst particles.